PREDICTION OF THE ENERGY VALUES OF COMPOUND FEEDS FOR RUMINANTS

Estimation of the net energy value of compound feeds for ruminants is important for both the feed compounder and the farmer. It is thus nece ssary to predict these values with good accuracy and at a low cost. Th is study concerned 83 compound feeds which are as representative as po ssible of the variety generally in use. The range of their organic mat ter digestibility was 65-90%. Samples of the feeds were studied in viv o in France by INRA Theix (17) and Paris (18), in The Netherlands by I VVO at Lelystad (24) and in the UK by the Rowett Research Institute at Aberdeen (24). All laboratories measured organic matter (OM) and ener gy digestibility. In addition, urinary energy losses and methane losse s were measured at Theix and the Rowett Institute. Cell wall (crude fi bre and neutral detergent fibre), lignocellulose (acid detergent fibre ). acid detergent lignin (ADL) and Christian lignin contents were dete rmined as well as enzymatic degradability. The net energy value of com pound feeds was calculated by a step-wise analytical procedure. At eac h step, the maximum amount of in vivo data was used, after their relia bility had been checked. This approach led to the formulation of equat ions predicting the net energy content expressed in net energy value f or milk (NE1) or for meat production (NE(mf)) with respective residual standard deviations varying from 0.350-0.446 MJ NE1 kg-1 OM and from 0.455-0.547 MJ NE(mf) kg-1 OM according to the analytical criteria con sidered. The major interest of this study lies in the fact that numero us in vivo measurements were performed, that a large number of laborat ory methods were used and that the compound feeds were representative of the variability generally in use at the present time.